The present invention relates to a sealing unit with a mounting error preventing construction which is realized by mounting an annular sealing member in a circumferential groove formed on an outer circumference of a cylindrical member.
A connector for connecting electric wires or optical fibers together has a watertight and airtight construction realized by sealing a space between two connecting portions by a seal member, so as to prevent the infiltration of water and dust (refer, for example, to Patent Document 1). In general, in a connector having a watertight construction or airtight construction, a connecting portion of a housing which constitutes a seal structure is formed into a cylindrical shape, and of two cylindrical connecting portions which are male and female housings, the male housing is inserted into an inner circumference of the female housing for connection. The sealing member seals a space defined between the inner circumference and an outer circumference of these cylindrical connecting portions.
For example, in a seal structure in which an annular sealing member is provided on a male housing side, a circumferential groove into which the sealing member is to fit is formed on an outer circumference of a cylindrical member of a male housing. The sealing member, which is formed of an elastic material such as rubber, is elastically deformed to be expanded in diameter and is then contracted in diameter to be restored from the expanded condition in a predetermined mounting position so as to be mounted in the circumferential groove.
Incidentally, as is shown in FIG. 7, a sealing member 500 of this type has a plurality of ridge portions (hereinafter, referred to as “lips”) 501, 503 which are formed coaxially side by side along a direction which follows an axis G on an outer circumferential surface thereof to enhance the sealing performance. By this configuration, the sealing performance is enhanced by increasing the number of contact locations where the lips 501, 503 are brought into contact with an inner circumferential surface of a cylindrical member of a female housing so as to form something like multiple steps.
FIG. 8 is an enlarged sectional view of a main part taken along a plane which includes an axis of the sealing member.
Of the lips 501, 503, the lip 501 which constitutes a connecting side with at least the female housing is made up of sloping faces which differ in inclination angle between one side and the other side of the lip 501 along the direction which follows the axis G. Namely, a sloping surface 505 having a large inclination angle is disposed on a side which follows the direction in which the sealing member 500 is mounted on the male housing (refer to a direction indicated by a thick white arrow in FIG. 8), and a sloping surface 507 having a small (moderate) inclination angle is disposed on an opposite side to the sloping surface 505. In the male housing in which the sealing member 500 is mounted in the circumferential groove, when the female housing is fitted thereon, a fitting force is reduced at the moderate sloping surface 507 which is disposed on a side from which the female housing is fitted, so as to obtain good fitting properties.    [Patent Document 1] JP-A-2006-31961
In the related sealing member 500, however, the left and right sloping faces 505, 507 of the lip 501 having the angular shape are formed at the different inclination angles so as to reduce the fitting force with which the female housing is fitted on the mating male housing to thereby obtain good fitting properties. However, since the magnitudes of the inclination angles of the sloping faces 505, 507 are difficult to be visually determined, there has been caused a fear that the sealing member is mounted in an opposite mounting direction to the designed mounting direction. There has been concern that the fitting force is increased conversely in the event that the sealing member is erroneously mounted in the opposite direction. In addition, with the sealing member 500 which is formed of the elastic material, there has been a problem that a mounting error is easy to occur in which the sealing member 500 is attempted to be mounted in a turned over condition in which an inner circumferential face 509 and an outer circumferential face 511 are turned inside out.